1. Field of the Invention
The present disclosure relates to speed detection for rotating machines, and more particularly to permanent magnet alternator speed detection using current sense transformers.
2. Description of Related Art
Permanent magnet alternators are used in mechanical systems with moving components that can be manipulated to generate electrical power. For example, a three-phase electrical system can be derived from a rotating engine component or shaft to which a rotor of a permanent magnet alternator (PMA) is attached. The three-phase voltage source can be rectified and filtered to create a useable voltage bus for use by on board electronics.
In some applications, there is a need to monitor the speed of the associated mechanical component used to generate the electrical power. For example, the required speed to be monitored could be engine speed on an aircraft. Conventional speed detection for permanent magnet alternators has been done using diode detection circuitry. Diode detection circuitry generally provides output with a relatively low signal to noise ratio and a relatively low voltage detection level (e.g. less than about 1 volt). This can make such circuitry difficult to reliably implement in high current environments. Moreover, in some systems, the need for electrical isolation may require additional electrical components, such as optical isolators for example.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is a need in the art for speed detection devices for permanent magnet alternators with improved reliability. The present disclosure provides solutions to this need.